Fig. 4. Identification of genes expressed by arrested undifferentiated C2C12 muscle cells. (A) Differential display PCR analysis. Expression profiles of RNA from asynchronous (Mb) suspension-arrested (S) and differentiated (Mt) C2C12 cell cultures displayed by differential display PCR. (Mb and S were analyzed in duplicate.) The arrowhead indicates a fragment representing a cDNA expressed in arrested myoblasts but not in either asynchronous or differentiated cultures (see Fig. 4E). (B-E) Transcripts detected by differential display PCR fragments are enriched in synchronized C2C12 cells. Fragments excised from differential display PCR gels were labeled and used to probe 10 µg of total RNA from asynchronous myoblasts (Mb), arrested myoblasts (S) and myotubes (Mt). Each fragment (CF1-4) detected a unique transcript; all were expressed preferentially in synchronized cells. The sizes of the transcripts (B-E) are 3.5 kb (CF1/matrilin2), 2.2 kb (CF2/Znf216), 1.7 kb (CF3/TTP) and 1.4 kb (CF4/LIX). Positions of 28 and 18S rRNA are marked (-). L7 demonstrates equal loading of RNA.